May 2014 Review - Sydney

It was a very warm May for Sydney this year. Despite a slightly cooler start to the month, unseasonably warm weather dominated most of the final 3 weeks. The higher temperatures were accompanied by plenty of sun and quite dry conditions.

The graph below shows the monthly averages for the past 6 years plus the long term average.

May averages at Sydney Airport for the period 2009-2014 plus the long term average

May 2014 was easily the highest of the past 6 years, and well above the long term average also. In the end, the average minimum for May this year of 13.0C was the equal 5th highest since records began in 1939. 1989 holds the record with 13.3C. Meanwhile, the average maximum was the 3rd highest since 1939. 1958 holds this record with 22.8C.

In the middle of May I wrote a post about how Sydney was on track to record its warmest May on record. Despite the weather station at the Airport falling short, Observatory Hill did record its warmest average maximum on record. The 23.2C average easily surpassed the 1958 record of 22.7C, with records dating back to 1859. The average minimum of 13.1C was the equal 12th warmest.

As this Special Climate Statement from the Bureau of Meteorology points out, a high pressure system sat in the Tasman Sea for an unusually long period of around 2 weeks. This led to warm temperatures throughout most of Australia, and especially in the south east.

The most significant record for Sydney was that Observatory Hill recorded 19 consecutive May days at or above 22C. This more than doubled the previous record of 9. The number of May days above 20C, 30, was also a record, beating 2013's 27.

At the Airport, there were 11 days above 25C. In the previous 5 editions of May, the highest figure was 4 in 2012. 2009 and 2011 recorded no days above 25C. While the number of days above 25C was quite high, the overall monthly high of 26.5C was still below previous years. That was recorded on both May 22 and 23. The highest minimum, however, was the highest in the past 6 years. The temperature on May 27 never went below 16.3C.

The coldest day was May 3 with a maximum of only 15.9C. The figure itself wasn't especially unusual, but fact that this was recorded so early in the month was. 2009 didn't see a maximum that low until June 10. The lowest temperature of the month of 10.1C was recorded quite early also, on the 5th. This is the highest overall minimum for May at the Airport on record.

Rainfall was well below average for 2014. The Airport saw the 9th driest May since 1930. BoM's recording of 17.6mm, and my recording of 18.0mm, were far below the average of 98.7mm.

Daily rainfall totals during May 2014

There were 8 days on which rain was recorded. May 11 to 13 was the longest streak for rain days. May 13 was also responsible for the highest daily total with 7.0mm. Starting May 14 though, there were 17 straight days without rain. This is the longest dry spell so far this year and the longest since the 35 day period between August 10 and September 13 last year.

Wind gusts were once again down on last year's figures. The average of the strongest daily gusts was 38.5km/h compared to 42.8km/h last year. May 4 saw the strongest monthly gust of 65km/h. The 18th saw a strongest gust of only 20km/h.